The principal goal of this research is to develop a solid phase radioimmunoassay of melatonin and to demonstrate its applicability for the analysis of picogram quantities of melatonin in plasma and cerebral spinal fluid. Several different melatonin analogs will be synthesized and coupled to bovine serum albumin for use in preparing antibodies for the radioimmunoassay. (H3)-Labeled melatonin of high specific activity will be obtained by a new procedure. Radioimmunoassays for the principal metabolites of melatonin, 6-hydroxymelatonin and 6-sulfatoxymelatonin will also be undertaken.